Abstract

Some retail payment systems can be modelled as two-sided markets, where a payment system facilitates money exchanges between consumers on one side and merchants on the other. The system sets rules and standards, to ensure usage and acceptance of its payment instruments by consumers and merchants respectively. Some retail payment systems exhibit indirect network externalities, which is one of the main criteria used to define two-sided markets. As more consumers use the payment platform, more merchants are encouraged to join it. Conversely, the value of holding payment instruments increases with the number of merchants accepting them. The theory of two-sided markets contributes to a better understanding of these retail payment systems, by showing that an asymmetric allocation of costs is needed to maximise the volume of transactions. It also starts to offer results that could explain competition between payment platforms. However, this theory entails some limits to a thorough understanding of retail payment systems. Firstly, we show that some retail payment systems, such as credit transfer or direct debit systems, do not necessarily fulfil all the theoretical criteria used to define twosided markets. Moreover, this theory does not take into account specific features of the payment industry, such as risk management or fraud prevention. This leads us to propose new research directions.